Generally, most vehicles have various kinds of suspension systems. The suspension system absorbs all sorts of shock generated when the vehicle is driving to improve stability of the vehicle and ride comfort. One type of such suspension system is an air suspension system using an air spring.
The air suspension system is able not only to absorb shock but also to uniformly maintain vehicle height regardless of a change in the vehicle weight. The air suspension system is also able to absorb high frequency vibrations as well. Further, the elastic modulus of the air spring is automatically regulated by the change in compressed air in the air spring in accordance with the weight change.
The air suspension system generally has a leveling valve for balancing the left and right height of the vehicle. For example, when the vehicle is turning, the vehicle receives centrifugal force which tilts the vehicle outward. Accordingly, the air suspension system changes a relative distance between a lower arm connecting the vehicle chassis to the wheel carrier supporting the wheel and the vehicle chassis. Namely, from an outward wheel view, the vehicle tilts outward such that the chassis gets near the lower arm. Here, a link assembly connected to a lever for actuating the leveling valve detects this distance change and the leveling valve opens to supply compressed air from an air tank to an air spring. Thus, the air spring mounted on the outward wheel side swells to uniformly maintain the distance between the chassis and the lower arm. Consequently, the vehicle keeps balanced.
As described above, a conventional air suspension system keeps a vehicle body balanced. However, when the vehicle is turning, passengers in the vehicle experience a centrifugal force which causes the bodies of the passengers to tilt outward. Such tilting causes discomfort to the passengers. Further, in the case of a truck, if loaded goods on the truck tilt outward by the centrifugal force, the vehicle could roll over due to the centrifugal force acting on the goods.